The leading with the helmet was there to protect defenseless receivers not quarterbacks out of the pocket. Still a questionable call.

Ref has to make the call:

(f) If a player uses any part of his helmet (including the top/crown and forehead/”hairline” parts) or facemask to butt, spear, or ram an opponent violently or unnecessarily. Although such violent or unnecessary use of the helmet and facemask is impermissible against any opponent, game officials will give special attention in administering this rule to protecting those players who are in virtually defenseless postures, including but not limited to:

(1) Forcibly hitting the defenseless player’s head, neck, or face with the helmet or facemask, regardless of whether the defensive player also uses his arms to tackle the defenseless player by encircling or grasping him; or

(2) Lowering the head and violently or unnecessarily making forcible contact with the “hairline” or forehead part of the helmet against any part of the defenseless player’s body; or

Roughing the passer was an absurd call, outside of the pocket technically makes him a runner btw. So now we have learned over the season, that you can't let any part of your helmet touch the QB's helmet, or its a penalty. And, we have learned that you can't let your helmet touch any part of their abdomen....where are defensive players supposed to tackle QB's? But what makes me even more angry, is the commentators trying to say its a correct call. What do you want to bet they were getting yelled at in their headsets not to make a big deal of it?

Edit: I forgot in the last few years we learned you can't touch a QB's legs either, sooooo what was Hardy supposed to do?

That was a beautiful play by Greg. Clean hit in my opinion. How can a defender dive to make a tackle without the head lowering? Carson Palmer is to blame for that violent hit, he should have thrown it away or gone down.